A method for controlling a device by using a rotation-rate sensor ascertains a rotation rate and controls the device as a function of the ascertained rotation rate and an acceleration variable, which is measured by an acceleration sensor. The device is, for example, a safety device such as a frontal airbag, a side airbag, or a rollover bar, which protects the occupant(s) of a motor vehicle in the event of rollover. To control the device, a triggering signal is determined in such a way that the side airbag is inflated and/or the rollover bar is extended if the motor vehicle rolls over. Extremely high reliability is necessary for the triggering of this safety device because the triggering of the safety device may cause an accident itself.
One disadvantage is that all existing signals, i.e., the rotation-rate variable and acceleration variable, are needed for the triggering. If one of the signals were faulty, the safety device could fail. For this reason, the method is monitored and checked for plausibility using various measures. In particular, if both signals were faulty, as would be the case for so-called common cause faults, the safety device could be triggered without a rollover occurring. The acceleration sensor and the rotation-rate sensor are therefore implemented in separate housings each having an analysis ASIC, in order to avoid shared fault paths because of one cause or external disturbance in both sensors at the same time. This increases the manufacturing costs.